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palantir / gradle-docker

a Gradle plugin for orchestrating docker builds and pushes.
Apache License 2.0
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docker gradle octo-correct-managed

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Docker Gradle Plugin

Build Status Gradle Plugins Release

Disclaimer: This Repo is now Defunct

Docker Plugin

This repository provides three Gradle plugins for working with Docker containers:

Apply the plugin using standard gradle convention:

plugins {
    id 'com.palantir.docker' version '<version>'
}

Set the container name, and then optionally specify a Dockerfile, any task dependencies and file resources required for the Docker build. This plugin will automatically include outputs of task dependencies in the Docker build context.

Docker Configuration Parameters

To build a docker container, run the docker task. To push that container to a docker repository, run the dockerPush task.

Tag and Push tasks for each tag will be generated for each provided tag and tags entry.

Examples

Simplest configuration:

docker {
    name 'hub.docker.com/username/my-app:version'
}

Canonical configuration for building a Docker image from a distribution archive:

// Assumes that Gradle "distribution" plugin is applied
docker {
    name 'hub.docker.com/username/my-app:version'
    files tasks.distTar.outputs   // adds resulting *.tgz to the build context
}

Configuration specifying all parameters:

docker {
    name 'hub.docker.com/username/my-app:version'
    tags 'latest' // deprecated, use 'tag'
    tag 'myRegistry', 'my.registry.com/username/my-app:version'
    dockerfile file('Dockerfile')
    files tasks.distTar.outputs, 'file1.txt', 'file2.txt'
    buildArgs([BUILD_VERSION: 'version'])
    labels(['key': 'value'])
    pull true
    noCache true
}

Managing Docker image dependencies

The com.palantir.docker and com.palantir.docker-compose plugins provide functionality to declare and resolve version-aware dependencies between docker images. The primary use-case is to generate docker-compose.yml files whose image versions are mutually compatible and up-to-date in cases where multiple images depend on the existence of the same Dockerized service.

Specifying and publishing dependencies on Docker images

The docker plugin adds a docker Gradle component and a docker Gradle configuration that can be used to specify and publish dependencies on other Docker containers.

Example

plugins {
    id 'maven-publish'
    id 'com.palantir.docker'
}

...

dependencies {
    docker 'foogroup:barmodule:0.1.2'
    docker project(":someSubProject")
}

publishing {
    publications {
        dockerPublication(MavenPublication) {
            from components.docker
            artifactId project.name + "-docker"
        }
    }
}

The above configuration adds a Maven publication that specifies dependencies on barmodule and the someSubProject Gradle sub project. The resulting POM file has two dependency entries, one for each dependency. Each project can declare its dependencies on other docker images and publish an artifact advertising those dependencies.

Generating docker-compose.yml files from dependencies

The com.palantir.docker-compose plugin uses the transitive dependencies of the docker configuration to populate a docker-compose.yml.template file with the image versions specified by this project and all its transitive dependencies. The plugin uses standard Maven/Ivy machanism for declaring and resolving dependencies.

The generateDockerCompose task generates a docker-compose.yml file from a user-defined template by replacing each version variable by the concrete version declared by the transitive dependencies of the docker configuration. The task performs two operations: First, it generates a mapping group:name --> version from the dependencies of the docker configuration (see above). Second, it replaces all occurrences of version variables of the form {{group:name}} in the docker-compose.yml.template file by the resolved versions and writes the resulting file as docker-compose.yml.

The docker-compose plugin also provides a dockerComposeUp task that starts the docker images specified in the dockerComposeFile in detached mode. You can also use the dockerComposeDown task to stop the containers.

Example

Assume a docker-compose.yml.template as follows:

myservice:
  image: 'repository/myservice:latest'
otherservice:
  image: 'repository/otherservice:{{othergroup:otherservice}}'

build.gradle declares a dependency on a docker image published as 'othergroup:otherservice' in version 0.1.2:

plugins {
    id 'com.palantir.docker-compose'
}

dependencies {
    docker 'othergroup:otherservice:0.1.2'
}

The generateDockerCompose task creates a docker-compose.yml as follows:

myservice:
  image: 'repository/myservice:latest'
otherservice:
  image: 'repository/otherservice:0.1.2'

The generateDockerCompose task fails if the template file contains variables that cannot get resolved using the provided docker dependencies. Version conflicts between transitive dependencies of the same artifact are handled with the standard Gradle semantics: each artifact is resolved to the highest declared version.

Configuring file locations

The template and generated file locations are customizable through the dockerCompose extension:

dockerCompose {
    template 'my-template.yml'
    dockerComposeFile 'my-docker-compose.yml'
}

Docker Run Plugin

Apply the plugin using standard gradle convention:

plugins {
    id 'com.palantir.docker-run' version '<version>'
}

Use the dockerRun configuration block to configure the name, image and optional command to execute for the dockerRun tasks:

dockerRun {
    name 'my-container'
    image 'busybox'
    volumes 'hostvolume': '/containervolume'
    ports '7080:5000'
    daemonize true
    env 'MYVAR1': 'MYVALUE1', 'MYVAR2': 'MYVALUE2'
    command 'sleep', '100'
    arguments '--hostname=custom', '-P'
}

Docker Run Configuration Parameters

Tasks

License

This plugin is made available under the Apache 2.0 License.

Contributing

Contributions to this project must follow the contribution guide.